Progress in electronic systems has resulted in a steady increase over the past few years in the amount of information supplied to car drivers, and therefore in a growing need to organize and display this information for quick access by the driver without overly distracting the driver's attention from the road.
The problem of displaying information without distracting the driver's attention from the road applies in particular to GPS navigation systems, which indicate routes using data supplied by a satellite positioning device. In fact, the tendency is for drivers to focus their attention continually on the route mapped on the GPS screen, as opposed to road traffic conditions, with obvious risks in terms of safety. It is important to note that, to monitor the GPS screen, the driver typically must look away from the road, and switching back and forth between the road and screen takes time for the driver's eyes to adapt to different focal lengths, which may be particularly slow in the case of elderly drivers.
By way of a solution to the problem, GPSs with a voice capability have been proposed, to communicate the route vocally to the driver. The effectiveness of voice communication, however, is limited, in that the driver still tends to monitor the GPS screen.
Another proposed solution is an HUD (Heads-Up Display) system, which projects an electronic image of the GPS-generated route information onto the windshield of the car, so the driver can read the projected information without looking away from the windshield, i.e. the road.
Installing an HUD system in a car, however, is an expensive process, and is therefore limited to a small number of top-range models. One of the major problems in installing an HUD system in a car is caused by flaws in the windshield, which, though not noticeable when observing the road through the windshield, may introduce unacceptable distortion of the projected images. As a result, the windshield (which has an extensive surface area and highly complex curved shape) often must be made to strict manufacturing specifications involving a considerable increase in cost and rejects.
Moreover, in normal driving conditions, the driver's head and, therefore, eyes are subject to continual vertical and horizontal bobbing movements induced by vibration of the car, so the driver's eyes must keep continual track of the position of the image projected on the windshield, thus making monitoring of the image awkward.
DE10034381 discloses an information display system for use in a road vehicle and having an image data projected onto a road surface in front of the vehicle.
DE10134594 discloses a lighting system for assisting a vehicle driver and having a lighting unit, a unit to modulate lighting, sensors to detect a driving situation and a control unit to control lighting modulation through a detected driving situation.
EP1334869 discloses a beam radiator that radiates visible light beams having a predetermined wavelength onto a road surface to inform drivers of other vehicles of the existence of a vehicle or to let a driver of the vehicle confirming a traveling path thereof.